1. Field of the Invention
The present invention relates to a reproducing apparatus and a reproducing method for checking forged information of a file recorded in a detachable memory card.
2. Description of the Related Art
EEPROM (Electrically Erasable Programmable ROM) that is an electrically rewritable memory requires a large space because each bit is composed of two transistors. Thus, the integration of EEPROM is restricted. To solve this problem, a flash memory that allows one bit to be accomplished with one transistor using all-bit-erase system has been developed. The flash memory is being expected as a successor of conventional record mediums such as magnetic disks and optical discs.
A memory card using a flash memory is also known. The memory card can be freely attached to an apparatus and detached therefrom. A digital audio recording/reproducing apparatus that uses a memory card instead of a conventional CD (Compact Disc: Trademark) or MD (Mini Disc: Trademark) can be accomplished.
On the other hand, as audio/video information is digitized and used for multi-media, the copyright protection thereof is becoming important. In the field of information services, the user will be provided with a record medium on which digitized audio/video information having particular reproduction limitation information has been recorded. In addition, digitized audio/video information having particular reproduction limitation information will be circulated to the user through digital broadcast and Internet. The user can reproduce provided or circulated audio/video information (contents) for the duration or the number of times represented by the reproduction limitation information. When necessary, the user can record desired audio/video information to a memory card at a predetermined cost.
Although a file containing reproduction limitation information is easily recorded and stored, if the reproduction limitation information is forged with a particular means, the reproducing side cannot detect the forged reproduction limitation information. As a simple method for detecting forged reproduction limitation information, CRC (Cyclic Redundancy Check) and a value obtained therewith can be used. However, after reproduction limitation information has been forged, if CRC is forged, the forged reproduction limitation information cannot be detected.